1. Field of the Invention
The present general inventive concept relates to a power management method of a semiconductor device, and more particularly, to a method of controlling a power saving mode, and a power management method used in a serial advanced technology attachment (SATA) interface.
2. Description of the Related Art
A serial advanced technology attachment (SATA) protocol on an interface for data transmission between a host and a device supports a power saving mode in order to reduce power consumption for a SATA interface method. The host, such as a motherboard or an interface card, serves as an interface in a personal computer, and the device, such as a hard disk drive (HDD), serves as data storage.
Referring to FIGS. 1 and 2, a power saving method according to the SATA protocol will be described below. A host or a device that is to enter a power saving mode transmits a power saving mode request signal (defined as expand the meaning of this acronym here PMREQ_P signal and expand the meaning of this acronym here PMREQ_S signal in the SATA protocol, and illustrated as the PMREQ signal in FIGS. 1 and 2) to the device or the host. Hereinafter, a side that transmits the PMREQ signal will be referred to as a transmitter, and a side that receives the PMREQ signal will be referred to as a receiver.
FIG. 1 is a data flow diagram of a power saving method when a host is a transmitter and a device is a receiver, and FIG. 2 is a data flowchart of a power saving method when a device is transmitter and a host is a receiver. The transmitter, as described above, transmits the PMREQ signal to the receiver. After receiving the PMREQ signal, the receiver transmits a PMACK signal in the SATA protocol to the transmitter when it is possible to enter the power saving mode, or transmits a PMNCK signal in the SATA protocol (not shown) to the transmitter when it is not possible to enter the power saving mode.
When the transmitter receives the PMACK signal, the transmitter and the receiver enter the power saving mode by turning off some or all PHY blocks of the transmitter and the receiver. In this case, a PHY block is a block defined in a SATA interface standard and denotes a physical layer. The PHY blocks are control blocks provided in the transmitter and the receiver for the SATA interface and may be classified as a block for controlling data transmission and reception, a PLL block, a block for generating finite state machine and clock, and the like depending on functions of the PHY blocks.
A system maintains the power saving mode until the transmitter or the receiver transmits a request for an end of the power saving mode through a COMWAKE signal of SATA protocol. Referring to FIG. 1, as the device transmits the COMWAKE signal to the host in response to the COMWAKE signal of the host, the power saving mode ends. Then, the host and the device enter an idle mode in order to prepare for data transmission and reception.
On the other hand, referring to FIG. 2, as the device transmits the COMWAKE signal to the host, the power saving mode ends. Hence, the host may request for the end of the power saving mode first through the COMWAKE signal that is represented by the dotted line in FIG. 2.
The SATA protocol supports two types of power saving modes: a slumber mode and a partial mode. According to the SATA standard, the slumber mode has a wake-up time of 10 ms, and the partial mode has a wake-up time of 10 us.
The partial mode turns off fewer PHY blocks as compared with the slumber mode, and thus, has a wake-up time faster than that of the slumber mode. The partial mode may turn off only PHY blocks associated with the above-described data transmission and reception, and the slumber mode may turn off more PHY blocks such that the faster wake-up time can be realized in the partial mode. Hence, a fast wake-up response can be realized in the partial mode as compared to the slumber mode, and more power can be saved in the slumber mode as compared to the partial mode.
The transmitter predicts the required time to request the receiver to enter one of the partial mode and the slumber mode. The receiver turns off the PHY blocks corresponding to the received mode such that the transmitter and the receiver enter the power saving mode as described above.
FIG. 3 is a flowchart of a power saving method 300 in a SATA protocol according to related art.
Referring to FIG. 3, whether the receiver has received the PMREQ_P signal in operation S320 is determined. The transmitter transmits the PMREQ_P signal in the partial mode, and transmits the PMREQ_S signal in the slumber mode. When the PMREQ_P signal is received by the receiver, the receiver checks whether it is possible to enter the partial mode in operation S321 in order to transmit the PMACK signal to the transmitter when it is possible to enter the partial mode, in operation S322, and transmits the PMNAK signal to the transmitter when it is not possible to enter the partial mode, in operation S324. When the transmitter receives the PMACK signal, the system enters the partial mode in operation S323.
When the PMREQ_P signal is not received by the receiver, whether the receiver received the PMREQ_S signal is checked, in operation S340. When the PMREQ_S signal is received by the receiver, the receiver checks whether it is possible to enter the slumber mode in operation S341 in order to transmit the PMACK signal to the transmitter when it is possible to enter the slumber mode, in operation S342, and transmits the PMNAK signal to the transmitter when it is not possible to enter the slumber mode, in operation S344. When the transmitter receives the PMACK signal, the system enters the slumber mode in operation S343.
When the power saving mode is not requested, that is, when neither the PMREQ_P signal nor the PMREQ_S signal is received, the transmitter and the receiver stays in the idle mode in operation S360.
However, the properties required of a system should be realized independently of the requested power saving mode. In detail, it is necessary to enter the slumber mode in order to reduce power consumption although the partial mode is requested. Similarly, it is necessary to enter the partial mode in order to improve the wake-up response although the slumber mode is requested. Thus, it may be necessary to operate in another mode besides the partial mode and the slumber mode depending on the properties of the system.